Developer information - usability related brainstorming

For full-featured tuningsoftware, there is a reliance on the use of a Laptop or PDA. Anyone serious will use that.

The 350 Euro (like MAF / MAP substitute, BoostController) market is different: PDA or PC can be an offputting aspect for many as a large number of potential users will have to the aquire the additional equipment.

Note that the target audience in the future will be less skilled than GenBoard/VerThree users.

For simple displays, we like

for medium:

Small buttons possible, of course.

while for more serious,

seems like the way to go.


LCD 4x20 is a bit tight. We can tune anything with it, but a newbie finds it hard.

We must seriously evaluate the use of a graphical LCD screen - like the one used for this [blackfin beast]

It's not a good solution to have the display on the control unit.

The other solution is to make a reliable feed of (possibly used) PDA-s. If it's just 98 Euro, noone will have a problem. But 400 Euro for something that they'd use just for tuning - I agree that's too much.

Sharp OZ-590 80 x 111 dot display with backlight $35 (can we get code in it?)

GBA $79.99

But any time we look, again and again... we always find that we cannot find a display for the price we can buy a PDA. TODO: collect links...

Please help find affordable LCD-s, weather just graphic LCD-s (50..100 pieces) or with CPU and memory like a game, learn-aid or PDA. We prefer devices with 6+ buttons (not just touchscreen).

some manufacturers are unlikely to cooperate (so we don't buy from them). But some might provide half-finished product with some documentation (eg. type and used ports of main CPU).

It seems it should be possible to get color graphic LCD-s for 60..120 Euro, probably with CPU and memory. Some porting will be needed for megatunix in any case, but we prefer buying sg. to own design.


The 5 button interface (up, down, left, right and OK) has some problems:

5 buttons is too few anyway. It could work, but rather a workaround than a good solution. It's possible to maintain good usability on 4+4+2 buttons (besides power, sound amplitude and backlight) in OtherTuningSoftware/NintendoGameBoy though.

On the other hand our CNC improved a lot lately, so there is no problem with a few buttons (Bourns SDTM 610 or 620 or 630 SMD buttons preferred).

I think that a PS2 keyboard (4 Euro) is affordable for everyone, and much more convenient than 5 buttons. You don't need the keyboard after the unit is tuned.

[using LEDs as output and input]

[half duplex circuit with 1 LED] from [this edn page] I thought of a probably better design: the problem (without actually building it) is R8 tuning would likely significantly depend on LED temperature. By applying the same signal to IC1B+ as on IC1B- (except lowpass filtered with an RC of course), we could make it autotune itself. D1 can be dropped, we can disable UART interrupt in firmware.

[|7163299|8017749 Bourns products] the [SDTM button pdf] is most applicable here. Please elaborate on the usability.

6-button interface example for use together with a 4x20 character LCD

This is basically the same that we have now. Anything can be done with it. Conveniently? No, the tables cannot be tuned conveniently. Acceptable for other configuration though.

Character LCD in display mode:

Rpm:4000  MAP:052kPa
L:0.97 EGT:750 C:093
OilP:480kPa OilT:099
TPS:16% IAT:025 

Switch screens with the arrow buttons and go to the menu mode by pressing the select key.

Character LCD in menu mode:


Use the arrow buttons and the select key to go to a menu. Use the ?back? button to return to the display mode.

Character LCD in table mode:

100% 060|080|090|095
080% 060|080|090|095
050% 060|080|090|095

Use the arrow keys to browse, press select key to edit a cell. In edit mode use the arrow keys to change the value, use back to discard change and select to store it. While holding the select key you can copy the value to an adjacent cell with the arrow keys.

Also, LCD is good for many things, but many variables are much more visible on a round gauge (eg. lambda, EGT) than in numeric. We shouldn't settle for less than graphical LCD, and for the price of graphical LCD a PDA can be bought with CPU + mem + input device + serial comm.

The onboard 6 buttons interface question is still up: do the gains justify it? I can't imagine how I'd push the buttons in the engine-bay when tuning ignition while the driver is driving. I don't feel safe near the engine bay of a car on a dyno (with cause).

Even after 1.5 years

If we can make a 6-button menu, we can - for sure - make the same (even literally the same menu is possible) for a graphic LCD device. The reverse is not true.

Round gauges are provenly the best when the reading time is considered. This had been studied extensively for military pilots. Also best for fluctuations (tricks are possible if not physical gauges are used but an LCD).

Graphic LCD makes it possible to choose between fastest read round gauges, fiat-typo style barlines or digital. 4x20 or any size alphanumerical LCD forces something that is good for many things, but far from ideal when tuning a map.


The Apexi fuel controller that I got a chance to use the other evening had a very simple text menu system that makes the system accessable for almost everyone. Could we describe the menu structure of it?

See also

Note: from GRMracer

I found a supplier that can do low volume custom LCD displays for reasonable prices.

ie. a combination LCD screen for gauges, Text, or just a plain TFT display. Cost is reasonable (quantity cost for the glass section should be around $20.00 ea , for a 1/2 DIN plate ie. stereo replacement) and turn around is about 2-3 mo..